Multilayer ceramic capacitor

ABSTRACT

In a multilayer ceramic capacitor, when a ratio of an ICP peak intensity of Mn to an ICP peak intensity of Ti is an Mn/Ti peak intensity ratio, a value of the Mn/Ti peak intensity ratio in a dielectric ceramic layer in at least one of a main surface outer layer portion, a side surface outer layer portion, and an end surface outer layer portion is in a range of two times to fifteen times a value of the Mn/Ti peak intensity ratio in a dielectric ceramic layer in a central portion of an effective portion in a width direction, a length direction, and a stacking direction.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application claims priority to Japanese Patent ApplicationNo. 2020-001059, filed Jan. 7, 2020, the entire contents of which isincorporated herein by reference.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to a ceramic capacitor, and specificallyto a multilayer ceramic capacitor having a structure in which aplurality of dielectric ceramic layers and a plurality of internalelectrode layers are stacked.

Description of the Background Art

There are conventionally widely used multilayer ceramic capacitors eachhaving a structure in which a multilayer body including a stack of aplurality of dielectric ceramic layers and a plurality of internalelectrode layers has both end surfaces having respective externalelectrodes disposed thereon and electrically conduct to the internalelectrode layers.

Japanese Patent Laid-Open No. 2006-73623 discloses a multilayer ceramiccapacitor having the above-mentioned structure. The multilayer ceramiccapacitor includes an element body formed by alternately stackingdielectric ceramic layers and internal electrode layers. At least one ofeach dielectric ceramic layer and each internal electrode layer has adifferent phase containing an Mg element and an Mn element.

According to Japanese Patent Laid-Open No. 2006-73623, theabove-described configuration allows implementation of a multilayerceramic capacitor having low IR temperature dependence and excellentaverage lifetime characteristics.

SUMMARY OF THE INVENTION

However, in the structure of the multilayer ceramic capacitor disclosedin Japanese Patent Laid-Open No. 2006-73623, the internal electrodelayers are smaller in plane surface area than the dielectric ceramiclayers. Thereby, a level difference exists between each dielectricceramic layer and the peripheral edge portion of each internal electrodelayer, excluding a portion of each internal electrode layer that extendsto reach the end surface of the element body. Thus, the internalelectrode layer may be bent due to this level difference, therebyleading to problems that a short circuit tends to occur between theinternal electrode layers, and the high-temperature load reliabilitytends to decrease.

In particular, as thinner dielectric ceramic layers are provided and alarger number of internal electrode layers and dielectric ceramic layersare stacked, a short circuit between the internal electrode layers ismore likely to occur, so that the reliability tends to decrease.

Thus, a multilayer ceramic capacitor has been manufactured by stackingceramic green sheets each prepared to have no level difference between aregion where an internal electrode pattern to be formed as an internalelectrode layer after firing is formed and a region where no internalelectrode pattern is formed (such a ceramic green sheet will behereinafter also referred to as a “zero level difference sheet”).

Specifically, for example, a conductive paste is applied to a prescribedregion on a ceramic green sheet to thereby form an internal electrodepattern that is to be formed as an internal electrode layer afterfiring. Then, a ceramic paste is applied to a region having no internalelectrode paste formed thereon, to form a ceramic layer for leveldifference elimination, to thereby form ceramic green sheets each havingno level difference between a region having an internal electrodepattern as an internal electrode layer formed thereon and a regionhaving no internal electrode pattern formed thereon. Then, these ceramicgreen sheets are stacked to form a multilayer body. A method for forminga multilayer body in this way has been known.

Even in this case, however, due to extremely small gaps or the likeexisting between each internal electrode pattern and each ceramic greensheet for level difference elimination, a bent portion may be formed insome of the internal electrode layers of the multilayer body obtainedafter firing, which may cause cracking and chipping in the multilayerbody, deterioration in high-temperature load reliability, and the like.

Thus, it is desirable to take measures for suppressing or preventingoccurrence of the above-described problems in a multilayer ceramiccapacitor.

The present invention has been made in order to solve theabove-described problems, and an object of the present invention is toprovide a multilayer ceramic capacitor that is less likely to causecracking and chipping in a multilayer body and that is excellent inhigh-temperature load reliability.

In order to solve the above-described problems, a multilayer ceramiccapacitor according to the present invention includes: a multilayer bodyincluding a plurality of dielectric ceramic layers and a plurality ofinternal electrode layers that are alternately arranged in a stack,wherein the dielectric ceramic layers each contain Ba, Ti, Mn, and arare earth element. The multilayer body has: (a) a first main surfaceand a second main surface that face each other in a stacking directionin which the dielectric ceramic layers and the internal electrode layersare stacked; (b) a first side surface and a second side surface thatface each other in a width direction orthogonal to both the stackingdirection and a direction in which the internal electrode layers extendto reach a surface of the multilayer body; and (c) a first end surfaceand a second end surface that face each other in a length directionorthogonal to both the stacking direction and the width direction. Firstand second external electrodes are disposed on each of the first endsurface and the second end surface, respectively, and electricallyconnected to alternate first and second sets of the plurality ofinternal electrode layers. A region where the internal electrode layersoverlap with each other in a view seen in the stacking direction isdefined as an effective portion, each of regions sandwiching theeffective portion in the stacking direction is defined as a main surfaceouter layer portion, each of regions sandwiching the effective portionin the width direction is defined as a side surface outer layer portion,and each of regions sandwiching the effective portion in the lengthdirection is defined as an end surface outer layer portion.

Assuming that a ratio of a peak intensity of Mn by laser ICP(inductively coupled plasma) to a peak intensity of Ti by laser ICP isdefined as an Mn/Ti peak intensity ratio, a value of the Mn/Ti peakintensity ratio in the dielectric ceramic layer in at least one of themain surface outer layer portion, the side surface outer layer portion,and the end surface outer layer portion is in a range of two times tofifteen times the value of the Mn/Ti peak intensity ratio in thedielectric ceramic layer in a central portion of the effective portionin the width direction, the length direction, and the stackingdirection.

In the multilayer ceramic capacitor of the present invention, the peakintensity ratio of Mn to Ti is set higher in the dielectric ceramiclayer in at least one of the main surface outer layer portion, the sidesurface outer layer portion, and the end surface outer layer portionthan in the dielectric ceramic layer in the central portion of theeffective portion in the width direction, the length direction, and thestacking direction. Thus, a multilayer ceramic capacitor that is lesslikely to have structural defects and cracking or chipping and that isexcellent in high-temperature load reliability can be provided.

The foregoing and other objects, features, aspects and advantages of thepresent invention will become more apparent from the following detaileddescription of the present invention when taken in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a multilayer ceramic capacitor accordingto one embodiment of the present invention.

FIG. 2 is a cross-sectional view of the multilayer ceramic capacitorshown in FIG. 1, which is taken along a line II-II.

FIG. 3 is a diagram schematically showing the state of internalelectrode layers in the multilayer ceramic capacitor according to oneembodiment of the present invention.

FIG. 4 is a diagram illustrating positions of main surface outer layerportions and end surface outer layer portions of the multilayer ceramiccapacitor according to one embodiment of the present invention.

FIG. 5 is a diagram illustrating positions of side surface outer layerportions and end surface outer layer portions of the multilayer ceramiccapacitor according to one embodiment of the present invention.

FIG. 6A is a diagram illustrating a method of fabricating a zero leveldifference sheet used to manufacture the multilayer ceramic capacitoraccording to the embodiment of the present invention.

FIG. 6B is a diagram illustrating the method of fabricating the zerolevel difference sheet used to manufacture the multilayer ceramiccapacitor according to the embodiment of the present invention.

FIG. 7 is a diagram showing one step in a method of manufacturing amultilayer ceramic capacitor according to one embodiment of the presentinvention.

FIG. 8 is a diagram showing another step in the method of manufacturinga multilayer ceramic capacitor according to one embodiment of thepresent invention.

FIG. 9 is a diagram showing another step in the method of manufacturinga multilayer ceramic capacitor according to one embodiment of thepresent invention.

FIG. 10A is a diagram illustrating a method of fabricating a zero leveldifference sheet according to a modification.

FIG. 10B is a diagram illustrating a method of fabricating a zero leveldifference sheet according to a modification.

FIG. 11 is a diagram illustrating a method of measuring thicknesses ofdielectric ceramic layers and internal electrode layers.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

With reference to embodiments of the present invention, features of thepresent invention will be specifically described below.

FIG. 1 is a perspective view of a multilayer ceramic capacitor accordingto one embodiment of the present invention, and FIG. 2 is a frontcross-sectional view thereof.

As shown in FIGS. 1 and 2, a multilayer ceramic capacitor 10 entirelyhas a rectangular parallelepiped shape, and includes: a multilayer body3 having a stack of a plurality of dielectric ceramic layers 1 and aplurality of internal electrode layers 2 (2 a, 2 b); and an externalelectrode 4 (4 a, 4 b) disposed at a prescribed position of multilayerbody 3 so as to electrically conduct to internal electrode layers 2.

Multilayer body 3 includes: (a) a first main surface 13 a and a secondmain surface 13 b facing each other in a stacking direction T in whichdielectric ceramic layers 1 and internal electrode layers 2 are stacked;(b) a first side surface 14 a and a second side surface 14 b facing eachother in a width direction W orthogonal to both stacking direction T anda direction in which internal electrode layers 2 extend to reach thesurface of multilayer body 3 (i.e., a length direction L describedbelow); and (c) a first end surface 15 a and a second end surface 15 bfacing each other in length direction L orthogonal to both stackingdirection T and width direction W.

Internal electrode layers 2 include: a first internal electrode layer 2a extending to reach first end surface 15 a of multilayer body 3; and asecond internal electrode layer 2 b extending to reach second endsurface 15 b of multilayer body 3.

Furthermore, a first external electrode 4 a of external electrode 4 isdisposed on first end surface 15 a so as to electrically conduct tofirst internal electrode layer 2 a extending to reach first end surface15 a. Also, a second external electrode 4 b is disposed on second endsurface 15 b so as to electrically conduct to second internal electrodelayer 2 b extending to reach second end surface 15 b.

Specifically, first external electrode 4 a is formed over the entirefirst end surface 15 a of multilayer body 3 and formed so as to extendfrom first end surface 15 a partially over first main surface 13 a,second main surface 13 b, first side surface 14 a, and second sidesurface 14 b.

Also, second external electrode 4 b is formed over the entire second endsurface 15 b of multilayer body 3 and formed so as to extend from secondend surface 15 b partially over first main surface 13 a, second mainsurface 13 b, first side surface 14 a, and second side surface 14 b.

Multilayer ceramic capacitor 10 according to the present embodiment hasdimensions including: a dimension in length direction L of about 0.35mm; a dimension in width direction W of about 0.28 mm; a dimension instacking direction T of about 0.28 mm; a thickness of about 0.5 μm inthe dielectric ceramic layer; and a thickness of about 0.30 μm in theinternal electrode layer.

Multilayer ceramic capacitor 10 according to the present embodiment ismanufactured through a process of stacking a plurality of ceramic greensheets on which internal electrode patterns to be formed as internalelectrode layers 2 after firing are respectively disposed.

Each ceramic green sheet having an internal electrode pattern disposedthereon is formed as a ceramic green sheet 1 a having no leveldifference on ceramic green sheet 11 between a region where internalelectrode pattern 12 to be formed as internal electrode layer 2 afterfiring is formed and a region where no internal electrode pattern 12 isformed (see FIG. 6B), as will be described below.

More specifically, in the present embodiment, as shown in FIG. 6A, aconductive paste for internal electrode layer is applied onto ceramicgreen sheet 11 to thereby form internal electrode pattern 12. Then, asshown in FIG. 6B, a ceramic paste layer 11 a is formed on a region whereno internal electrode pattern 12 is formed, to thereby fabricate aceramic green sheet having no level difference between a region whereinternal electrode pattern 12 is formed and a region where no internalelectrode pattern 12 is formed, i.e., fabricate a zero level differencesheet 1 a.

Then, as shown in FIG. 7, a prescribed number of zero level differencesheets 1 a are stacked in such a manner that internal electrode patterns12 to be formed as internal electrode layers after firing extend toreach the opposite sides alternately.

A multilayer body is formed specifically by: stacking a prescribednumber of ceramic green sheets 21 a each having no internal electrodepattern formed thereon and used for forming a main surface outer layerportion on the lower side; stacking a prescribed number of theabove-mentioned zero level difference sheets 1 a each having internalelectrode pattern 12 formed thereon; stacking a prescribed number ofceramic green sheets 21 b each having no internal electrode patternformed thereon and used for forming a main surface outer layer portionon the upper side; and then press-fitting the resultant stack. Thus, anunfired multilayer body 3 a is fabricated that has a structure in whichinternal electrode patterns 12 extend to reach facing end surfaces 15alternately, and in which internal electrode patterns 12 are exposedalso on facing side surfaces 14, as shown in FIG. 8.

Then, as shown in FIG. 9, an unfired and coated multilayer body 3 b isobtained by attaching a ceramic green sheet 122 to each of facing sidesurfaces 14 (FIG. 8) of unfired multilayer body 3 a, through whichinternal electrode patterns 12 are exposed, so as to place ceramic greensheet 122 to cover these side surfaces 14 (FIG. 8) through whichinternal electrode patterns 12 are exposed.

Then, unfired and coated multilayer body 3 b is fired to obtain a firedmultilayer body 3. Then, as shown in FIGS. 1 and 2, first externalelectrode 4 a and second external electrode 4 b are formed on first endsurface 15 a and second end surface 15 b, respectively, of multilayerbody 3 so as to electrically conduct to internal electrode layers 2 (2a, 2 b) exposed on first end surface 15 a and second end surface 15 b,respectively, of multilayer body 3. Thus, multilayer ceramic capacitor10 is obtained.

In addition to the method of forming one multilayer body 3 described inthe present embodiment, for example, a so-called multi-piece formingmethod may be used to manufacture individual multilayer bodies byseparately dividing a mother multilayer body, as will be describedbelow.

First, a mother multilayer body is formed by stacking, in a prescribedmanner: a prescribed number of mother green sheets used for forming anouter layer portion on the lower side and having no internal electrodepattern formed thereon; a prescribed number of mother green sheetshaving strip-shaped mother internal electrode patterns respectivelyformed thereon that are to be formed as internal electrodes formultilayer bodies; and a prescribed number of mother green sheets usedfor forming an outer layer portion on the upper side and having nointernal electrode pattern formed thereon.

Then, the obtained mother multilayer body is divided at prescribedpositions to thereby fabricate an unfired multilayer body 3 a having astructure in which internal electrode patterns 12 extend to reach facingend surfaces 15 alternately, and in which internal electrode patterns 12are exposed also on facing side surfaces 14, as shown in FIG. 8.

Then, as shown in FIG. 9, ceramic green sheet 122 is attached to each offacing side surfaces 14 of unfired multilayer body 3 a, which is thenfired to thereby form a fired multilayer body. Then the externalelectrodes are formed on the end surfaces 15, with the result that aplurality of multilayer ceramic capacitors are then fabricated.

According to the above-mentioned method, when the mother multilayer bodyis divided at prescribed positions, the strip-shaped mother internalelectrode pattern is cut at a plurality of prescribed positions in thedirection orthogonal to the longitudinal direction, thereby formingindividual unfired multilayer bodies 3 a in which internal electrodepatterns 12 are exposed also on the side surfaces, as shown in FIG. 8.

Multilayer ceramic capacitors are generally manufactured by such amulti-piece forming method. The multilayer ceramic capacitor of thepresent invention can also be manufactured efficiently by thismulti-piece forming method.

In multilayer ceramic capacitor 10 according to the present embodiment,multilayer body 3 is formed using ceramic green sheet (zero leveldifference sheet) la having no level difference on ceramic green sheet11 between a region where the internal electrode pattern 12 is formed(and converted into internal electrode layer 2 after firing) and aregion where no internal electrode pattern 12 is formed, as describedabove. In this case, as schematically shown in FIG. 3, a bent portion 30is formed in an extending portion 2 a 1 of first internal electrodelayer 2 a that extends to reach first end surface 15 a. Although thereason why such bent portion 30 is formed is unclear, it is presumedthat bent portion 30 as mentioned above is formed in the press-fittingstep due to distortion or the like caused by a gap or the like formedamong internal electrode pattern 12 in FIG. 6B, the region whereinternal electrode pattern 12 is formed, the region where no internalelectrode pattern is formed, and ceramic paste layer 11 a foreliminating a level difference therearound. In a conventional multilayerceramic capacitor not having the configuration of the present invention(described later), this bent portion 30 causes structural defects,cracking and chipping, and a deterioration in high-temperature loadreliability.

In multilayer ceramic capacitor 10 according to the present embodiment,a dielectric ceramic layer 1 in an effective portion 20 as a regionwhere internal electrode layers 2 overlap with each other in a view seenin stacking direction T is made of a ceramic material containing Ba, Ti,Mn, and a rare earth element. More specifically, dielectric ceramiclayer 1 is made of a ceramic material containing: BaTiO₃ as a maincomponent; Mn; holmium (Ho) as a rare earth element; and V and Zr asminor components.

Although holmium (Ho) is used as a rare earth element in the presentembodiment, other rare earth elements such as dysprosium (Dy), yttrium(Y), and lanthanoid other than holmium (Ho) can also be used alone or incombination, for example. However, in the present invention, it isparticularly preferable to use holmium (Ho), dysprosium (Dy), andyttrium (Y) as rare earth elements.

Internal electrode layer 2 (i.e., first internal electrode layer 2 a andsecond internal electrode layer 2 b) is formed of metals such as Ni, Cu,Ag, Pd, Ti, Cr, and Au, or an alloy of these metals, for example.Internal electrode layer 2 may contain, as coexisting materials,dielectric ceramic particles having the same or similar composition asthat of ceramic contained in dielectric ceramic layer 1.

In multilayer ceramic capacitor 10 according to the present embodiment,external electrode 4 (i.e., first external electrode 4 a and secondexternal electrode 4 b) includes a first Ni layer 41 as an underlyingelectrode layer and a second Ni layer 42 as a plating layer formed onfirst Ni layer 41.

First Ni layer 41 constituting external electrode 4 is formed, forexample, by applying and baking a conductive paste formed of glass andcontaining Ni as a main conductive component.

Second Ni layer 42 constituting external electrode 4 is formed byapplying Ni plating onto the surface of first Ni layer 41 as anunderlying electrode layer.

External electrode 4 is configured to include first Ni layer 41 that isa baked electrode as an underlying electrode and second Ni layer 42 as aplating layer on the surface of first Ni layer 41, thereby allowingfabrication of a highly reliable multilayer ceramic capacitor includingan external electrode that is bonded to multilayer body 3 with highstrength and that has a dense surface to achieve excellent moistureresistance.

Baking of the conductive paste during formation of first Ni layer 41 maybe performed simultaneously with firing of multilayer body 3. Also,after firing of multilayer body 3, a conductive paste may be applied tomultilayer body 3, which may then be baked.

First Ni layer 41 as an underlying electrode layer contains, as acoexisting material, dielectric ceramic particles (dielectriccomposition particles) having the same or similar composition as that ofthe dielectric ceramic constituting dielectric ceramic layer 1 (adielectric composition constituting dielectric ceramic) in a ratio of25% by area to 40% by area.

When first Ni layer 41 as an underlying electrode layer contains acoexisting material in a ratio of 25% to 40% by area in this way,physical properties such as an expansion coefficient of the externalelectrode can be brought close to those of the multilayer body. Thus,occurrence of defects such as cracks can be suppressed and thereliability can be improved. However, an excessively high content ratioof the coexisting material may decrease the electrical conductivity.Accordingly, it is desirable that the content ratio of the coexistingmaterial does not exceed 40% by area.

The materials forming external electrode 4 and the method of formingexternal electrode 4 are not limited to the above-described examples,and external electrode 4 can be formed by various known methods usingvarious materials used for forming electrodes.

Alternatively, an Sn layer may be formed by Sn plating on second Nilayer 42 or a solder plating layer may be formed by solder plating onsecond Ni layer 42, thereby also allowing improvement in solderabilityof external electrode 4.

In samples of Examples 1 to 34 that each are multilayer ceramiccapacitor 10 according to the embodiment of the present invention shownin the following Table 1, a region where internal electrode layers 2overlap with each other in stacking direction T is defined as effectiveportion 20, each of regions sandwiching effective portion 20 in stackingdirection T is defined as a main surface outer layer portion 21, each ofregions sandwiching effective portion 20 in width direction W is definedas a side surface outer layer portion 22, and each of regionssandwiching effective portion 20 in length direction L is defined as anend surface outer layer portion 23, as shown in FIGS. 4 and 5. In thiscase, assuming that a ratio of a peak intensity of Mn by laser ICP to apeak intensity of Ti by laser ICP is defined as an Mn/Ti peak intensityratio, a value of the Mn/Ti peak intensity ratio in the dielectricceramic layer in at least one of main surface outer layer portion 21,side surface outer layer portion 22, and end surface outer layer portion23 is in a range of two times to fifteen times the value of the Mn/Tipeak intensity ratio in the dielectric ceramic layer in a centralportion of effective portion 20 in width direction W, length directionL, and stacking direction T.

An applicable method for increasing the value of the Mn/Ti peakintensity ratio in the dielectric ceramic layer in at least one of mainsurface outer layer portion 21, side surface outer layer portion 22, andend surface outer layer portion 23 in a range of two times to fifteentimes the value of the Mn/Ti peak intensity ratio in the dielectricceramic layer in the central portion of effective portion 20 mayinclude, for example, a method of using ceramic green sheets, asdielectric ceramic layers forming a main surface outer layer portion oras dielectric ceramic layers forming side surface outer layer portion22, that are higher in ratio of Mn to Ti than the dielectric ceramiclayers used for forming an effective portion.

Furthermore, as an alternatively applicable method, a paste, powder orthe like containing Mn as a main component may be applied onto theoutside of the dielectric ceramic layer constituting main surface outerlayer portion 21 or the outside of the dielectric ceramic layerconstituting side surface outer layer portion 22, and firmly adhered tothe chip surface, and then diffused during degreasing and firing.

Furthermore, in the samples of Examples 18 to 34 among the samples ofExamples 1 to 34 in Table 1 that are fabricated in the presentembodiment, assuming that a ratio of the peak intensity of Ho (a rareearth element) by laser ICP to the peak intensity of Ti by laser ICP isdefined as a Ho (rare earth element)/Ti peak intensity ratio, the valueof the Ho (rare earth element)/Ti peak intensity ratio in the dielectricceramic layer in at least one of main surface outer layer portion 21,side surface outer layer portion 22, and end surface outer layer portion23 is set to be higher than the value of the Ho (rare earth element)/Tipeak intensity ratio in the dielectric ceramic layer in the centralportion in effective portion 20.

Examples of an applicable method for increasing the values of the Ho(rare earth element)/Ti peak intensity ratios in the dielectric ceramiclayers in main surface outer layer portion 21, side surface outer layerportion 22, and end surface outer layer portion 23 in a range of twotimes to fifteen times the value of the Ho (rare earth element) peakintensity ratio in the dielectric ceramic layer in the central portionof effective portion 20 may include a method of using ceramic greensheets, as dielectric ceramic layers constituting the main surface outerlayer portion or as dielectric ceramic layers constituting side surfaceouter layer portion 22, that are higher in ratio of Ho (a rare earthelement) to Ti than the dielectric ceramic layers used for forming aneffective portion.

Furthermore, as an alternatively applicable method, a paste or powdercontaining Ho (a rare earth element) as a main component may be appliedonto the outside of the dielectric ceramic layer constituting mainsurface outer layer portion 21 or the outside of the dielectric ceramiclayer constituting side surface outer layer portion 22, and firmlyadhered to the chip surface, and then, diffused during degreasing andfiring.

With regard to the multilayer ceramic capacitors in Examples 1 to 34fulfilling the requirements of the present invention, and the multilayerceramic capacitors in Comparative Examples 1 to 5 not fulfilling therequirements of the present invention, each of which is fabricated inthe present embodiment, Table 1 shows: the value of the Mn/Ti peakintensity ratio as a ratio of the peak intensity of Mn by laser ICP(laser atomic emission spectroscopy) to the peak intensity of Ti bylaser ICP in each of the effective portion, the main surface outer layerportion, the end surface outer layer portion, and the side surface outerlayer portion in each of the above-mentioned multilayer ceramiccapacitors in Examples 1 to 34 and Comparative Examples 1 to 5; and thevalue of the Ho/Ti peak intensity ratio as a ratio of the peak intensityof Ho by laser ICP to the peak intensity of Ti by laser ICP in each ofthe effective portion, the main surface outer layer portion, the endsurface outer layer portion, and the side surface outer layer portion ineach of the above-mentioned multilayer ceramic capacitors in Examples 1to 34 and Comparative Examples 1 to 5.

TABLE 1 Structural Structural Defects on Defects on Mn/Ti Peak Ho/TiPeak Side End Cracking Intensity Ratio Intensity Ratio Surface Surfaceand Main Side End Main Side End Side Side Chipping Surface SurfaceSurface Surface Surface Surface Number of Number of Number of StructuralEffec- Outer Outer Outer Effec- Outer Outer Outer Occur- Occur- Occur-Defect MTTF tive Layer Layer Layer tive Layer Layer Layer rences rencesrences Evaluation 120° C. Portion Portion Portion Portion PortionPortion Portion Portion (N = 50) (N = 50) (N = 100) Result 6.3 V Compar-1 1 1 1 1 1 1 1 0 0 9 Not Good 21 ative Example 1 Example 1 1 2 1 1 1 11 1 0 0 1 Good 23 Example 2 1 5 1 1 1 1 1 1 0 0 1 Good 25 Example 3 1 101 1 1 1 1 1 0 0 1 Good 27 Example 4 1 15 1 1 1 1 1 1 0 0 1 Good 27Compar- 1 20 1 1 1 1 1 1 12 12 13 Not Good 27 ative Example 2 Example 51 1 2 1 1 1 1 1 0 0 1 Good 27 Example 6 1 1 5 1 1 1 1 1 0 0 1 Good 32Example 7 1 1 10 1 1 1 1 1 0 0 1 Good 36 Example 8 1 1 15 1 1 1 1 1 0 01 Good 38 Compar- 1 1 20 1 1 1 1 1 16 0 18 Not Good 38 ative Example 3Example 9 1 1 1 2 1 1 1 1 0 0 1 Good 25 Example 10 1 1 1 4 1 1 1 1 0 0 1Good 27 Example 11 1 1 1 7 1 1 1 1 0 0 1 Good 32 Example 12 1 1 1 10 1 11 1 0 0 1 Good 36 Example 13 1 1 1 13 1 1 1 1 0 0 1 Good 36 Compar- 1 11 20 1 1 1 1 0 13 17 Not Good 36 ative Example 4 Example 14 1 2 2 2 1 11 1 0 0 1 Good 29 Example 15 1 5 5 4 1 1 1 1 0 0 1 Good 36 Example 16 110 10 7 1 1 1 1 0 0 1 Good 46 Example 17 1 15 15 10 1 1 1 1 0 0 1 Good42 Compar- 1 30 30 20 1 1 1 1 21 14 29 Not Good 42 ative Example 5Example 18 1 10 10 7 1 2 1 1 0 0 0 Good 45 Example 19 1 10 10 7 1 5 1 10 0 0 Good 47 Example 20 1 10 10 7 1 7 1 1 0 0 0 Good 47 Example 21 1 1010 7 1 10 1 1 1 1 1 Good 47 Example 22 1 10 10 7 1 1 2 1 0 0 0 Good 44Example 23 1 10 10 7 1 1 5 1 0 0 0 Good 46 Example 24 1 10 10 7 1 1 7 10 0 0 Good 46 Example 25 1 10 10 7 1 1 10 1 1 0 1 Good 46 Example 26 110 10 7 1 1 1 2 0 0 0 Good 43 Example 27 1 10 10 7 1 1 1 4 0 0 0 Good 44Example 28 1 10 10 7 1 1 1 5 0 0 0 Good 44 Example 29 1 10 10 7 1 1 1 70 0 0 Good 44 Example 30 1 10 10 7 1 1 1 10 0 1 1 Good 45 Example 31 110 10 7 1 2 2 2 0 0 0 Good 50 Example 32 1 10 10 7 1 5 5 4 0 0 0 Good 50Example 33 1 10 10 7 1 7 7 5 0 0 0 Good 50 Example 34 1 10 10 7 1 7 7 100 0 1 Good 48

The peak intensity ratio in Table 1 was obtained by the method describedbelow.

First, for obtaining the peak intensity ratio in effective portion 20,multilayer ceramic capacitor 10 was cut at a central part G (see FIGS.2, 4, and 5) in length direction L along width direction W and stackingdirection T to expose the cross section of effective portion 20. Theexposed cross section was then analyzed by laser ICP. The spot diameter(irradiation diameter) of laser ICP was set at about 15 μm. Theeffective portion was analyzed at each of three points in the upper,intermediate, and lower portions in the stacking direction, to obtain anaverage value of the peak intensities of each of Ti and Ho (a rare earthelement).

Then, the respective average values of the peak intensities of each ofMn, Ti, and Ho (a rare earth element) obtained at the above-mentionedthree points were used to calculate the Mn/Ti peak intensity ratio as aratio of the peak intensity of Mn to the peak intensity of Ti, and theHo/Ti peak intensity ratio as a ratio of the peak intensity of Ho (arare earth element) to the peak intensity of Ti.

Furthermore, the peak intensities of Ti, Mn, and Ho in the dielectricceramic layer in each of main surface outer layer portion 21, sidesurface outer layer portion 22, and end surface outer layer portion 23were measured in each of main surface outer layer portion 21, sidesurface outer layer portion 22, and end surface outer layer portion 23along the planes exposed by cutting multilayer ceramic capacitor 10 atcentral part Gin length direction L (see FIGS. 2, 4, and 5) along widthdirection W and stacking direction T in the same manner as in theabove-mentioned case of measuring the peak intensity in the effectiveportion.

It should be noted that the numerical values of the Mn/Ti peak intensityratio and the Ho/Ti peak intensity ratio in a corresponding portion ineach of the main surface outer layer portion, the side surface outerlayer portion, and the end surface outer layer portion in Table 1 do notexactly show the values of the Mn/Ti peak intensity ratio and the Ho/Tipeak intensity ratio in each corresponding portion, but show the valuesobtained by normalizing the Mn/Ti peak intensity ratio and the Ho/Tipeak intensity ratio in each corresponding portion based on the Mn/Tipeak intensity ratio and the Ho/Ti peak intensity ratio in the effectiveportion each defined as 1.

Table 1 also shows the number of occurrences of structural defects onthe side surface side and structural defects on the end surface sideexamined in each of 50 samples, the number of occurrences of crackingand chipping examined in each of 100 samples, and the mean time tofailure (MTTF) in the high-temperature load reliability test performedin each of 30 samples.

The structural defects on the side surface side in Table 1 representstructural defects observed in a portion on the side surface side alonga W-T plane defined in width direction W and stacking direction T, whichis exposed by polishing multilayer body 3 from the end surface side tothe central portion in length direction L.

The structural defects on the end surface side in Table 1 representstructural defects observed in a portion on the end surface side alongan L-T plane defined in length direction L and stacking direction T,which is exposed by polishing multilayer body 3 from the side surfaceside to the central portion in width direction W.

The structural defects on the side surface side and the structuraldefects on the end surface side include, for example, delamination,cracking, and the like. In this case, based on delamination or crackingextending along a length equal to or more than the thickness of thedielectric ceramic layers constituting the effective portion, a samplerecognized as having such delamination or cracking in the portion on theside surface side is defined as having structural defects on the sidesurface side, and also, a sample recognized as having such delaminationor cracking in the portion on the end surface side is defined as havingstructural defects on the end surface side.

Table 1 shows the number of samples recognized as having structuraldefects as a result of observation of 50 samples for checking both thestructural defects on the side surface side and the structural defectson the end surface side.

Cracking and chipping in Table 1 mean a defect having a maximum diameterof 50 μm or more and visually recognized from outside (an externalstructure defect). Table 1 also shows the number of samples recognizedas having any defect having a maximum diameter of 50 μm or more as aresult of the examination for checking the external appearances of 100samples.

The structural defect evaluation result in Table 1 includes ratings of“Good” and “Not Good.” The rating of “Good” is for: a sample having noneof three types of defects that include structural defects on the sidesurface side, structural defects on the end surface side, and crackingand chipping (external structural defects); and a sample having lessthan two defects for each of the above-mentioned three types of defects.The rating of “Not Good” is for a sample having two or more defects forat least one type of defect among the above-mentioned three types ofdefects.

The mean time to failure (MTTF) as an index for determining thehigh-temperature load reliability is a mean value of the time periodselapsing after application of a voltage of 6.3 V to 30 samples in anatmosphere at a high temperature of 120° C. until occurrence of failuressuch as a short circuit or insulation resistance deterioration. When themean time to failure (MTTF) is shorter than a prescribed time, thehigh-temperature load reliability is determined as “Not Good.”

For example, when the dielectric ceramic layer is designed to have athickness of 0.5 μm, the prescribed time is set at 25 hours. When thedielectric ceramic layer is designed to have a thickness of 0.4 μm, theprescribed time is set at 20 hours. In the present embodiment, thedielectric ceramic layer has a thickness of about 0.5 μm. Thus, when theMTTF was less than 23 hours, the high-temperature load reliability wasevaluated as “Not Good.”

As shown in Table 1, in each of the samples of Examples 1 to 34fulfilling the requirement that the value of the Mn/Ti peak intensityratio in the dielectric ceramic layer in any one of the main surfaceouter layer portion, the side surface outer layer portion, and the endsurface outer layer portion is in a range of two times to fifteen timesthe value of the Mn/Ti peak intensity ratio in the dielectric ceramiclayer in the effective portion, the structural defect evaluation resultwas rated as “Good.”

Also as to the high-temperature load reliability, in each of the samplesof Examples 1 to 34, the MTTF was 23 hours or more, and thehigh-temperature load reliability was rated as “Good.”

On the other hand, in each of the samples of Comparative Examples 1 to 5not fulfilling the above-described requirement, the structural defectevaluation result was confirmed as “Not Good.”

As to the high-temperature load reliability, in Comparative Example 1,the MTTF was 21 hours and the high-temperature load reliability wasdetermined as “Not Good.” In each of Comparative Examples 2 to 5,however, the MTTF was 23 hours or more, and the high-temperature loadreliability was confirmed as “Good.”

Among the samples of Examples 1 to 34 fulfilling the above-describedrequirement, in each of the samples of Examples 14 to 17 fulfilling therequirement that the value of the Mn/Ti peak intensity ratio in thedielectric ceramic layer in each of the main surface outer layerportion, the side surface outer layer portion, and the end surface outerlayer portion was in a range of two times to fifteen times the value ofthe Mn/Ti peak intensity ratio in the dielectric ceramic layer in theeffective portion, the structural defect evaluation result wasdetermined as “Good,” and the high-temperature load reliability wasconfirmed as “Good.” It was recognized that the samples of Examples 16and 17 particularly tend to be improved in high-temperature loadreliability as compared with the samples of Examples 1 to 13 in whichthe value of the Mn/Ti peak intensity ratio in the dielectric ceramiclayer in only one of the main surface outer layer portion, the sidesurface outer layer portion, and the end surface outer layer portion isin a range of two times to fifteen times the value of the Mn/Ti peakintensity ratio in the dielectric ceramic layer in the effectiveportion.

Furthermore, among the samples of Examples 1 to 34 fulfilling therequirements of the present invention for the Mn/Ti peak intensityratio, in each of the samples of Examples 18 to 30 further fulfillingthe requirement that the value of the Ho (rare earth element)/Ti peakintensity ratio in the dielectric ceramic layer in any one of the mainsurface outer layer portion, the side surface outer layer portion, andthe end surface outer layer portion is in a range of two times or moreand ten times or less the value of the Ho (rare earth element)/Ti peakintensity ratio in the dielectric ceramic layer in the effectiveportion, each structural defect evaluation result was rated as “Good”,and the high-temperature load reliability was also recognized as havinga tendency to improve.

Among the samples of Examples 18 to 30, in each of the samples ofExamples 18 to 20, Examples 22 to 24, and Examples 26 to 29 in which thevalue of the Ho (rare earth element)/Ti peak intensity ratio in thedielectric ceramic layer in any one of the main surface outer layerportion, the side surface outer layer portion, and the end surface outerlayer portion was in a range of two times to seven times the value ofthe Ho (rare earth element)/Ti peak intensity ratio in the dielectricceramic layer in the effective portion, structural defects on the sidesurface side, structural defects on the end surface side, and crackingand chipping (external structural defects) were not observed. However,in each of the samples of Examples 21, 25, and 30 exhibiting a ten timeshigher Ho (rare earth element)/Ti peak intensity ratio, the number ofoccurrences of defects was as small as less than two, but structuraldefects on the side surface side, structural defects on the end surfaceside, and cracking and chipping (external structural defects) wereobserved. However, also in each of the samples of Examples 21, 25, and30 exhibiting a ten times higher Ho (rare earth element)/Ti peakintensity ratio, the structural defect evaluation result was rated as“Good.”

Therefore, the multilayer ceramic capacitor of the present invention isconfigured such that the value of the Ho (rare earth element)/Ti peakintensity ratio in the dielectric ceramic layer in any one of the mainsurface outer layer portion, the side surface outer layer portion, andthe end surface outer layer portion is preferably in a range of twotimes to ten times, and more preferably in a range of two times to seventimes, the value of the Ho (rare earth element)/Ti peak intensity ratioin the dielectric ceramic layer in the effective portion.

Furthermore, in each of the samples of Examples 31 to 33 in which thevalue of the Ho (rare earth element)/Ti peak intensity ratio in thedielectric ceramic layer in each of the main surface outer layerportion, the side surface outer layer portion, and the end surface outerlayer portion is in a range of two times to seven times the value of theHo (rare earth element)/Ti peak intensity ratio in the dielectricceramic layer in the effective portion, the structural defect evaluationresult was rated as “Good,” and the MTTF was 50 hours, so that thehigh-temperature load reliability was confirmed to achieve aparticularly good result. However, in the case of the sample of Example34 fulfilling the same conditions as those of the sample of Example 33except for the condition that the value of the Ho (rare earthelement)/Ti peak intensity ratio in the dielectric ceramic layer in theend surface outer layer portion was 10 times as high as the value of theHo (rare earth element)/Ti peak intensity ratio in the dielectricceramic layer in the effective portion, the structural defect evaluationresult and the high-temperature load reliability each were rated as“Good,” but the MTTF was 48 hours, so that it was confirmed that thehigh-temperature load reliability was slightly inferior to those of thesamples of Examples 31 to 33 for which the MTTF was 50 hours.

Therefore, it is recognized that the values of the Ho (rare earthelement)/Ti peak intensity ratios in the dielectric ceramic layers inthe main surface outer layer portion, the side surface outer layerportion, and the end surface outer layer portion are preferably in arange of two times to ten times, and more preferably in a range of twotimes to seven times, the value of the Ho (rare earth element)/Ti peakintensity ratio in the dielectric ceramic layer in the effectiveportion.

It is unclear why structural defects, and cracking and chipping are lesslikely to occur in the multilayer body and the high-temperature loadreliability is improved when the value of the Mn/Ti peak intensity ratioin the dielectric ceramic layer in at least one of the main surfaceouter layer portion, the side surface outer layer portion, and the endsurface outer layer portion is in a range of two times to fifteen timesthe value of the Mn/Ti peak intensity ratio in the dielectric ceramiclayer in the central portion of the effective portion as describedabove. The following reasons are however conceivable.

(a) Diffusion of Mn is promoted to thereby increase the ratio of Mn inthe end portions of the internal electrode layer in the width directionand the length direction, the grain growth of ceramic constituting thedielectric ceramic layer is suppressed, and the element smoothness isalso improved, with the result that the high-temperature loadreliability is improved.

(b) The grain growth of ceramic constituting the dielectric ceramiclayer is suppressed, and the grain size is reduced to thereby increasethe grain boundary, and thus, any external impact is readily absorbed,with the result that occurrence of cracking and chipping is reduced, andthe incidence of structural defects is reduced.

The above describes a feature that the values of the Mn/Ti peakintensity ratios in the dielectric ceramic layers in the main surfaceouter layer portion, the side surface outer layer portion, and the endsurface outer layer portion are in a range of two times to fifteen timesthe value of the Mn/Ti peak intensity ratio in the dielectric ceramiclayer in the effective portion. This feature is describedinterchangeably as that the ratios of Mn to Ti in the dielectric ceramiclayers in the main surface outer layer portion, the side surface outerlayer portion, and the end surface outer layer portion are set higherthan the ratio of Mn to Ti in the dielectric ceramic layer in theeffective portion. The ratio of Mn to Ti can be represented by a molarratio, for example.

It is not necessarily clear why the high-temperature load reliability isimproved by adjusting the values of the Ho (rare earth element)/Ti peakintensity ratios in the dielectric ceramic layers in the main surfaceouter layer portion, the side surface outer layer portion, and the endsurface outer layer portion to fall within a range of two times to 10times the value of the Ho (rare earth element)/Ti peak intensity ratioin the dielectric ceramic layer in the effective portion. However, it isconceivable that diffusion of Mn or Ho from the outer layer portion tothe inner layer improves the insulation property of ceramic in the innerlayer, thereby improving the reliability at the end portion of theelectrode where the electric field concentrates.

It should be noted that the above-mentioned range is desirable sincemerely increasing the ratio of Mn or a rare earth element such as Ho toTi causes sintering mismatch to thereby produce structural defects.

In the multilayer ceramic capacitor of the present invention, when thecontent ratios of Mn and a rare earth element in the dielectric ceramiclayer in each of the main surface outer layer portion, the side surfaceouter layer portion, the end surface outer layer portion, and theeffective portion are set such that Mn is more than 0 mol % and lessthan 5 mol % and the rare earth element is 0.1 mol % or more and lessthan 15 mol %, then, the Mn/Ti peak intensity ratio and the rare earthelement/Ti peak intensity ratio are desirably set at respective valuesas defined in the present invention.

Furthermore, in the above-described embodiment, the dielectric ceramiclayers are made of ceramic containing BaTiO₃ as a main component, andthereby, the content of Ti in each dielectric ceramic layer is about 20mol %. Thus, in the case where Ti is contained in such a ratio, Mn and arare earth element are set to be contained at prescribed sites so as torespectively achieve the Mn/Ti peak intensity ratio and the rare earthelement/Ti peak intensity ratio as described above, with the result thatthe functions and effect of the present invention can be achieved.

Zero level difference sheet 1 a used in the above-described embodimentis obtained by forming ceramic paste layer 11 a on a region having nointernal electrode pattern 12 formed thereon (i.e., a region on one endside of ceramic green sheet 11 in the longitudinal direction), therebyforming a ceramic green sheet having no level difference between aregion having internal electrode pattern 12 formed thereon and a regionhaving no internal electrode pattern 12 formed thereon (i.e., theabove-mentioned so-called zero level difference sheet 1 a), as shown inFIG. 6B. In contrast, for example, as shown in FIGS. 10A and 10B,ceramic paste layer 11 a is disposed around internal electrode pattern12 formed on the surface of ceramic green sheet 11 in such a manner thatonly one side of internal electrode pattern 12 extends to reach the endportion of ceramic green sheet 11, to thereby form zero level differencesheet 1 a configured such that no level difference exists between theregion having internal electrode pattern 12 formed thereon and theregion formed therearound and having no internal electrode pattern 12formed thereon. Zero level difference sheet 1 a formed in this way canalso be used. When zero level difference sheet 1 a shown in FIGS. 10Aand 10B is used, no internal electrode pattern is exposed on the sidesurface of the obtained multilayer body, thereby eliminating the need toaffix a ceramic sheet onto the side surface of the multilayer body.

Also in the case where zero level difference sheet 1 a shown in FIGS.10A and 10B is used, a so-called multi-piece forming method isapplicable, by which a mother multilayer body is formed by using amother green sheet having a plurality of internal electrode patternsformed thereon in matrix form, and cut at prescribed positions, andthen, divided into individual multilayer bodies. In this case, nointernal electrode pattern is exposed on the side surfaces of theobtained individual multilayer bodies, which eliminates the need toaffix ceramic sheets onto the side surfaces of the multilayer bodies, asdescribed above.

In addition, not only when the present invention is applied to amultilayer ceramic capacitor formed using the above-described so-calledzero level difference sheet, but also when the present invention isapplied to a multilayer ceramic capacitor manufactured using a ceramicgreen sheet having a level difference between a region having aninternal electrode pattern formed thereon and a region having nointernal electrode pattern formed thereon (i.e., a ceramic green sheeton which no ceramic paste layer for level difference elimination isformed), occurrence of cracking and chipping may be able to besuppressed, and the high-temperature load reliability may be able to beimproved.

Then, the dimensions of each of portions of the multilayer ceramiccapacitor to which the present invention is preferably applicable willbe described.

The preferable dimensions of the multilayer ceramic capacitor will behereinafter described by way of example.

<Dimensions of Each of Portions of Multilayer Ceramic Capacitor>

(Type 1)

Dimension in length direction L: 0.32 mm to 0.36 mm

Dimension in width direction W: 0.25 mm to 0.30 mm

Dimension in stacking direction T: 0.25 mm to 0.30 mm

Thickness of dielectric ceramic layer: 0.35 μm to 0.6 μm

Thickness of internal electrode layer: 0.30 μm to 0.4 μm

The thickness of the dielectric ceramic layer and the thickness of theinternal electrode layer show an average thickness of the dielectricceramic layers and an average thickness the internal electrode layers,respectively, in the effective portion.

(Type 2)

Dimension in length direction L: 0.1 mm to 0.12 mm

Dimension in width direction W: 0.63 mm to 0.68 mm

Dimension in stacking direction T: 0.62 mm to 0.68 mm

Thickness of dielectric ceramic layer: 0.35 μm to 0.6 μm

Thickness of internal electrode layer: 0.30 μm to 0.4 μm

The thickness of the dielectric ceramic layer and the thickness of theinternal electrode layer show an average thickness of the dielectricceramic layers and an average thickness of the internal electrodelayers, respectively, in the effective portion.

In the multilayer ceramic capacitor of the present invention, thethickness of the internal electrode layer is preferably 0.4 μm or less,and more preferably 0.3 μm or less, irrespective of the outer dimensionsthereof.

The internal electrode layer having a thickness of 0.4 μm or less allowsfurther thinning of layers, so that the capacity can be increased, andalso, peeling off due to a shrinkage difference between the internalelectrode and the dielectric layer can be prevented.

Although the internal electrode layer having a thickness of 0.3 μm orless can further reliably prevent peeling, the internal electrode layerhaving a thickness of 0.3 μm or more is usually desirable for thepurpose of ensuring coverage of the internal electrode layer.

Furthermore, in the multilayer ceramic capacitor of the presentinvention, the thickness of the dielectric ceramic layer is preferably0.6 μm or less. The dielectric ceramic layer having a thickness of 0.6μm or less allows formation of a multilayer ceramic capacitor having arelatively large capacitance.

However, for the purpose of preventing a short circuit between internalelectrode layers and a deterioration in high-temperature loadreliability, it is usually preferable that the dielectric ceramic layerhas a thickness of 0.1 μm or more.

<Method of Measuring Thicknesses of Dielectric Ceramic Layer andInternal Electrode Layer>

Then, a method of measuring thicknesses of the dielectric ceramic layerand the internal electrode layer will be described.

For example, when measuring the thickness of the dielectric ceramiclayer, a plurality of straight lines La, Lb, Lc, Ld, and a straight lineLe were drawn at prescribed intervals S from each other, as shown inFIG. 11. Then, a thickness Da on straight line La, a thickness Db onstraight line Lb, a thickness Dc on straight line Lc, a thickness Dd onstraight line Ld, and a thickness De on straight line Le were measuredand averaged to obtain an average value thereof, which was defined as athickness of the dielectric ceramic layer.

Similarly, when measuring the thickness of the internal electrode layer,a thickness Ea on straight line La, a thickness Eb on straight line Lb,a thickness Ec on straight line Lc, a thickness Ed on straight line Ld,and a thickness Ee on straight line Le shown in FIG. 11 were measuredand averaged to obtain an average value thereof, which was defined as athickness of the internal electrode layer.

For example, when calculating the average thickness of the plurality ofdielectric ceramic layers, the above-mentioned method was used tomeasure the thicknesses of five dielectric ceramic layers including: adielectric ceramic layer located substantially at the center in stackingdirection T; and two dielectric ceramic layers located on each of bothsides thereof. Then, the measured thicknesses were averaged to obtain anaverage value, which was defined as an average thickness of theplurality of dielectric ceramic layers. Also, when calculating theaverage thickness of the plurality of internal electrode layers, theabove-mentioned method was used to measure the thicknesses of fiveinternal electrode layers including: an internal electrode layer locatedsubstantially at the center in stacking direction T; and two internalelectrode layers located on each of both sides thereof. Then, themeasured thicknesses were averaged to obtain an average value, which wasdefined as an average thickness of the plurality of internal electrodelayers. When the number of stacked dielectric ceramic layers (internalelectrode layers) was less than five, the above-mentioned method wasused to measure the thicknesses of all the dielectric ceramic layers andthe internal electrode layers. Then, the measured thicknesses wereaveraged to obtain an average value, which was defined as an averagethickness of the plurality of dielectric ceramic layers and theplurality of internal electrode layers.

<Method of Measuring Coexisting Material in External electrode>

The content of the ceramic material as a coexisting material in thefirst Ni layer as an underlying electrode layer (i.e., the area ratio)is measured by the following method using a wavelength dispersive X-rayanalyzer (WDX). First, the cross section of the central region ofmultilayer ceramic capacitor 10 in width direction W is exposed, and theimage of the central region in the thickness direction in the first Nilayer as an underlying electrode layer in the central region ofmultilayer body 3 in stacking direction T is enlarged at a magnificationof 10000 times. The field of view of the enlarged region is 6 μm×8 μm.Then, the enlarged region is mapped by WDX, and the area ratio (% byarea) is measured based on the image obtained by mapping.

The present invention is not limited to the above-described embodiments,but various applications and modifications thereof can be made withinthe scope of the present invention.

Although the present invention has been described and illustrated indetail, it is clearly understood that the same is by way of illustrationand example only and is not to be taken by way of limitation, the scopeof the present invention being interpreted by the terms of the appendedclaims.

What is claimed is:
 1. A multilayer ceramic capacitor comprising: amultilayer body including a plurality of dielectric ceramic layers and aplurality of internal electrode layers that are alternately arranged ina stack, the plurality of dielectric ceramic layers each containing Ba,Ti, Mn, and a rare earth element, the multilayer body having: (a) afirst main surface and a second main surface that face each other in astacking direction in which the plurality of dielectric ceramic layersand the plurality of internal electrode layers are stacked; (b) a firstside surface and a second side surface that face each other in a widthdirection orthogonal to the stacking direction; and (c) a first endsurface and a second end surface that face each other in a lengthdirection orthogonal to both the stacking direction and the widthdirection; a first external electrode on the first end surface andelectrically connected to a first set of internal electrode layers ofthe plurality of internal electrode layers; and a second externalelectrode on the second end surface and electrically connected to asecond set of internal electrode layers of the plurality of internalelectrode layers, wherein a region where the first and second set ofinternal electrode layers overlap with each other in a view in thestacking direction is defined as an effective portion, each of regionssandwiching the effective portion in the stacking direction is definedas a main surface outer layer portion, each of regions sandwiching theeffective portion in the width direction is defined as a side surfaceouter layer portion, each of regions sandwiching the effective portionin the length direction is defined as an end surface outer layerportion, and a ratio of a peak intensity of Mn by laser ICP to a peakintensity of Ti by laser ICP is an Mn/Ti peak intensity ratio, a valueof the Mn/Ti peak intensity ratio in a dielectric ceramic layer in atleast one of the main surface outer layer portion, the side surfaceouter layer portion, and the end surface outer layer portion is in arange of two times to fifteen times a value of the Mn/Ti peak intensityratio in a dielectric ceramic layer in a central portion of theeffective portion in the width direction, the length direction, and thestacking direction.
 2. The multilayer ceramic capacitor according toclaim 1, wherein a ratio of a peak intensity of a rare earth element bylaser ICP to a peak intensity of Ti by laser ICP is a rare earthelement/Ti peak intensity ratio, a value of the rare earth element/Tipeak intensity ratio in the dielectric ceramic layer in the at least oneof the main surface outer layer portion, the side surface outer layerportion, and the end surface outer layer portion is in a range of twotimes to ten times the value of the rare earth element/Ti peak intensityratio in the dielectric ceramic layer in the central portion of theeffective portion.
 3. The multilayer ceramic capacitor according toclaim 2, wherein the value of the rare earth element/Ti peak intensityratio in the dielectric ceramic layer in the at least one of the mainsurface outer layer portion, the side surface outer layer portion, andthe end surface outer layer portion is in the range of two times toseven times the value of the rare earth element/Ti peak intensity ratioin the dielectric ceramic layer in the central portion of the effectiveportion.
 4. The multilayer ceramic capacitor according to claim 1,wherein the value of the Mn/Ti peak intensity ratio in the dielectricceramic layer in each of the main surface outer layer portion, the sidesurface outer layer portion, and the end surface outer layer portion isin the range of two times to fifteen times the value of the Mn/Ti peakintensity ratio in the dielectric ceramic layer in the central portionof the effective portion.
 5. The multilayer ceramic capacitor accordingto claim 4, wherein a ratio of a peak intensity of a rare earth elementby laser ICP to a peak intensity of Ti by laser ICP is a rare earthelement/Ti peak intensity ratio, a value of the rare earth element/Tipeak intensity ratio in the dielectric ceramic layer in the at least oneof the main surface outer layer portion, the side surface outer layerportion, and the end surface outer layer portion is in a range of twotimes to ten times the value of the rare earth element/Ti peak intensityratio in the dielectric ceramic layer in the central portion of theeffective portion.
 6. The multilayer ceramic capacitor according toclaim 5, wherein the value of the rare earth element/Ti peak intensityratio in the dielectric ceramic layer in the at least one of the mainsurface outer layer portion, the side surface outer layer portion, andthe end surface outer layer portion is in the range of two times toseven times the value of the rare earth element/Ti peak intensity ratioin the dielectric ceramic layer in the central portion of the effectiveportion.
 7. The multilayer ceramic capacitor according to claim 4,wherein a ratio of a peak intensity of a rare earth element by laser ICPto a peak intensity of Ti by laser ICP is a rare earth element/Ti peakintensity ratio, a value of the rare earth element/Ti peak intensityratio in the dielectric ceramic layer in each of the main surface outerlayer portion, the side surface outer layer portion, and the end surfaceouter layer portion is in a range of two times to ten times a value ofthe rare earth element/Ti peak intensity ratio in the dielectric ceramiclayer in the central portion of the effective portion.
 8. The multilayerceramic capacitor according to claim 7, wherein the value of the rareearth element/Ti peak intensity ratio in the dielectric ceramic layer ineach of the main surface outer layer portion, the side surface outerlayer portion, and the end surface outer layer portion is in the rangeof two times to seven times the value of the rare earth element/Ti peakintensity ratio in the dielectric ceramic layer in the central portionof the effective portion.
 9. The multilayer ceramic capacitor accordingto claim 1, wherein a ratio of a peak intensity of a rare earth elementby laser ICP to a peak intensity of Ti by laser ICP is a rare earthelement/Ti peak intensity ratio, a value of the rare earth element/Tipeak intensity ratio in the dielectric ceramic layer in each of the mainsurface outer layer portion, the side surface outer layer portion, andthe end surface outer layer portion is in a range of two times to tentimes a value of the rare earth element/Ti peak intensity ratio in thedielectric ceramic layer in the central portion of the effectiveportion.
 10. The multilayer ceramic capacitor according to claim 9,wherein the value of the rare earth element/Ti peak intensity ratio inthe dielectric ceramic layer in each of the main surface outer layerportion, the side surface outer layer portion, and the end surface outerlayer portion is in the range of two times to seven times the value ofthe rare earth element/Ti peak intensity ratio in the dielectric ceramiclayer in the central portion of the effective portion.
 11. Themultilayer ceramic capacitor according to claim 1, wherein the first andsecond external electrodes include: a first Ni layer on each of thefirst end surface and the second end surface of the multilayer body,respectively; a second Ni layer on the first Ni layer; and an Sn layeron the second Ni layer.
 12. The multilayer ceramic capacitor accordingto claim 1, wherein the plurality of internal electrode layers each havea thickness of 0.4 μm or less.
 13. The multilayer ceramic capacitoraccording to claim 1, wherein the plurality of internal electrode layerseach have a thickness of 0.3 μm or less.
 14. The multilayer ceramiccapacitor according to claim 1, wherein the plurality of dielectricceramic layers each have a thickness of 0.6 μm or less.
 15. Themultilayer ceramic capacitor according to claim 1, wherein the first andsecond external electrodes contain a dielectric composition of theplurality of dielectric ceramic layers in a ratio of 25% by area to 40%by area.